Synthesis, Crystal Structures, and Photochemical Properties of a Family of Heterometallic Titanium Oxo Clusters

The incorporation of heterometallic atoms into the structure of titanium-oxygen nanomaterials is one of the known and effective strategies to develop new high-performance photovoltaic active materials. In this study, we have synthesized three benzoic acid-stabilized heterometallic titanium oxo clusters with the different transition metals Co, Cu, and Cd, formulated as [Ti₄Co₂(μ₂-O)₂(μ₃-O)₂(C₆H₅COO)₁₂(CH₃CN)₂]·2CH₃CN (1), [Ti₅Cu₄(μ₃-O)₆(C₆H₅COO)₁₆] (2), and [Ti₁₂Cd₅(μ₂-O)(μ₃-O)₁₅(μ₄-O)₂(C₆H₅COO)₂₂(C₆H₅COOH)(CH₃CN)]·CH₃CN·C₆H₅COOH (3), and then we characterized their structures. UV-vis spectroscopy analysis revealed an enhanced UV-vis-light absorption of those heterometallic clusters. The density functional theory calculations indicated that charge transfer occurs from the p orbital of O atoms to the d orbital of Ti atoms in the TiO core (O → Ti) as well as from the metal to the core in 1 and 2. We also measured the photocurrent response and photocatalytic H₂ evolution, which shows enhancement in the photocurrent intensity and good H₂ evolution ability because of the cooperative effect of heterometal doping in titanium oxo clusters.